from flask import Flask
from flask import request
from flask import render_template

app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello, World!'

@app.route('/about')
def about():
    return 'This is the About Page.'

@app.route('/greet/<name>')
def greet(name):
    return f'Hello, {name}!'

@app.route('/submit', methods=['POST'])
def submit():
    username = request.form.get('username')
    return f'Hello, {username}!'

# Template
@app.route('/hello/<name>')
def hello(name):
    return render_template('index.html', name=name)

if __name__ == '__main__':
    app.run(debug=True)